sub pv1000border(tvl as ubyte):
  out $FF,tvl band $07
  '- try bor/band with existing one
  end sub

'- 76543210
'- ||||||||
'- |||||||+-- border (blue?)
'- ||||||+--- border (green?)
'- |||||+---- border (red?)
'- ||||+----- 
'- |||+------ bank (which one?)
'- ||+------- bank (which one?)
'- |+-------- 
'- +--------- 
